Integration of bonded optoelectronics, photonics waveguide and VLSI SOI

ABSTRACT

An optoelectronic device includes an integrated circuit including electronic devices formed on a front side of a semiconductor substrate. A barrier layer is formed on a back side of the semiconductor substrate. A photonics layer is formed on the barrier layer. The photonics layer includes a core for transmission of light and a cladding layer encapsulating the core and including a different index of refraction than the core. The core is configured to couple light generated from a component of the optoelectronic device.

BACKGROUND

Technical Field

The present invention relates to optoelectronic integration with verylarge scale integration (VLSI) devices, and more particularly tosystems, devices and methods for integrating optoelectronics andwaveguides on a backside of integrated circuit chips.

Description of the Related Art

Field effect transistors (FET) for very large scale integration (VLSI)are formed on a semiconductor substrate. While photonics devices oftenwork with VLSI FETs, integration of photonics functions with VLSIstructures requires use of valuable chip space or “real estate”. Thephotonics waveguides are usually integrated in a substrate layer (e.g.,Si layer) that is also employed for Si transistors. This complicates theVLSI design and processing.

SUMMARY

An optoelectronic device includes an integrated circuit includingelectronic devices formed on a front side of a semiconductor substrate.A barrier layer is formed on a back side of the semiconductor substrate.A photonics layer is formed on the barrier layer. The photonics layerincludes a core for transmission of light and a cladding layerencapsulating the core and including a different index of refractionthan the core. The core is configured to couple light generated from acomponent of the optoelectronic device.

Another optoelectronic device includes an integrated circuit includingelectronic devices formed on a front side of a semiconductor substrate.A light emitting device is connected to at least one of the electronicdevices. A barrier layer is formed on a back side of the semiconductorsubstrate. A photonics layer is formed on the barrier layer. Thephotonics layer includes a core for transmission of light and a claddinglayer encapsulating the core and including a different index ofrefraction than the core. The core is configured to couple lightgenerated by the light emitting device.

A method for fabricating an optoelectronic device includes forming abarrier layer on a back side of a semiconductor substrate, a front sideof the semiconductor substrate including an integrated circuit includingelectronic devices; and forming a photonics layer on the barrier layer,the photonics layer including a core for transmission of light and acladding layer encapsulating the core and including a different index ofrefraction than the core, the core configured to couple light generatedfrom at least one component of the optoelectronic device.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 is a cross-sectional view of an optoelectronic device having aphotonics layer formed on a thin barrier layer on an opposite side of anintegrated circuit and including a waveguide having a core floating in acladding layer in accordance with the present principles;

FIG. 2 is a cross-sectional view of an optoelectronic device having aphotonics layer formed on a thick barrier layer on an opposite side ofan integrated circuit and including a waveguide having a core in contactwith the barrier layer in accordance with the present principles;

FIG. 3 is a cross-sectional view of an optoelectronic device having theoptoelectronic devices of FIG. 1 and FIG. 2 coupled to a platform withthe optoelectronic device of FIG. 2 including a through via to connectto an additional integrated circuit in accordance with the presentprinciples;

FIG. 4 is a cross-sectional view of an optoelectronic device having alight emitting device bonded to a front side of an integrated circuitand a photonics layer with a core and a mirror to redirect light fromthe light emitting device in accordance with the present principles;

FIG. 5 is a cross-sectional view of an optoelectronic device having alight emitting device bonded to a front side of an integrated circuitand a photonics layer with a core, a transverse portion and a mirror toredirect light from the light emitting device in accordance with thepresent principles;

FIG. 6 is a cross-sectional view of an optoelectronic device having alight emitting device bonded to a front side of an integrated circuitand a photonics layer with a core with a coupling portion to redirectevanescent light from the light emitting device in accordance with thepresent principles;

FIG. 7 is a cross-sectional view of an optoelectronic device having alight emitting device bonded to a barrier layer on a back side of anintegrated circuit within a photonics layer, which includes a corealigned with the light emitting device to direct light in accordancewith the present principles;

FIG. 8 is a cross-sectional view of an optoelectronic device having alight emitting device bonded to a barrier layer on a back side of anintegrated circuit within a photonics layer, which includes a corealigned with the light emitting device to direct evanescent light inaccordance with the present principles; and

FIG. 9 is a block/flow diagram showing methods for fabricating of anoptoelectronic device in accordance with illustrative embodiments.

DETAILED DESCRIPTION

In accordance with the present principles, devices and methods areprovided that include photonic elements, such as e.g., waveguides, etc.that are integrated with an integrated circuit (IC) but on a backside orover a front side of the IC. This saves real-estate for very large scaleintegration (VLSI) circuits. The back side (or front side) of the IC maybe processed so as to not interfere with metallization structures foroff-chip electrical connections.

In useful embodiments, VLSI semiconductor-on-insulator (SOI) technologymay be employed with a thin silicon oxide (SiO₂) layer barrier having athickness T less than a light wavelength (λ) of the light transmitted. Alow refractive index layer needs to be deposited first (silicon oxide)to isolate a waveguide core from the VLSI circuitry. In other usefulembodiments, a thick silicon oxide (SiO₂) layer may be employed as abarrier having a thickness T greater than a light wavelength (λ) of thelight transmitted. A core can be deposited on the barrier. The coreincludes a refractive index higher than 1.56 (if SiO₂ is employed as1.56 is the refractive index of SiO₂).

The core or cores may be formed in or with a cladding layer. Otherphotonics components, connections and support circuitry may be locatedon the back (or front) of the IC along with the waveguide(s). Thephotonics components, though not being integrated directly with VLSIcircuitry, remain close and in many cases are closer to VLSI componentson the IC than in conventional structures.

It is to be understood that the present invention will be described interms of a given illustrative architecture; however, otherarchitectures, structures, substrate materials and process features andsteps may be varied within the scope of the present invention.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

The present embodiments may include a design for an integrated circuitchip, which may be created in a graphical computer programming language,and stored in a computer storage medium (such as a disk, tape, physicalhard drive, or virtual hard drive such as in a storage access network).If the designer does not fabricate chips or the photolithographic masksused to fabricate chips, the designer may transmit the resulting designby physical means (e.g., by providing a copy of the storage mediumstoring the design) or electronically (e.g., through the Internet) tosuch entities, directly or indirectly. The stored design is thenconverted into the appropriate format (e.g., GDSII) for the fabricationof photolithographic masks, which typically include multiple copies ofthe chip design in question that are to be formed on a wafer. Thephotolithographic masks are utilized to define areas of the wafer(and/or the layers thereon) to be etched or otherwise processed.

Methods as described herein may be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

It should also be understood that material compounds will be describedin terms of listed elements, e.g., SiGe. These compounds includedifferent proportions of the elements within the compound, e.g., SiGeincludes Si_(x)Ge_(1-x) where x is less than or equal to 1, etc. Inaddition, other elements may be included in the compound and stillfunction in accordance with the present principles. The compounds withadditional elements will be referred to herein as alloys.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIG. 1, a cross-sectional view of achip package 10 fabricated for transfer and having photonics and VLSIcircuitry is shown in accordance with one illustrative embodiment. Atemporary mechanical substrate 14 may include glass, quartz, Si,sapphire or any other suitable material employed to build and/ortransfer the chip package 10. An integrated circuit (IC) chip 16 isadhered to the mechanical substrate 14. The IC chip 16 may include anyintegrated circuit components including a VLSI array, processors,memory, photonic processing circuitry, etc.

A photonic waveguide layer 30 is integrated with the chip package byforming the photonic waveguide layer 30 on a backside of the IC chip 16to save real-estate for VLSI circuits on the chip 16. The photonicwaveguide layer 30 includes a core 22. Core 22 guides light therethroughand includes a high index of refraction relative to a cladding layer 24.The core 22 may include a polymer, SiN or other waveguide materials. Thecladding layer 24 may include any low index dielectric, SiO₂, polymer,porous materials, etc.

The photonic waveguide layer 30 is separated from the IC chip 16 by abarrier layer 18. The barrier layer 18 may include a thin layer of SiO₂(the thickness of the layer 18 should be less than the light wavelength(λ) to be transmitted by the core 22). The low refractive index layer orcladding 24 is deposited on the barrier layer 18 followed by theformation/deposition and patterning of the core 22. Then, more cladding24 is formed to encapsulate the core 22. The barrier layer 18 isolatesthe core 22 from the VLSI circuits of the IC chip 16.

Referring to FIG. 2, a cross-sectional view of a chip package 12fabricated for transfer and having photonics and VLSI circuitry is shownin accordance with another illustrative embodiment. The temporarymechanical substrate 14 may include glass, quartz, Si, sapphire or anyother suitable material employed to build and/or transfer the chippackage 12. IC chip 16 is adhered to the mechanical substrate 14. The ICchip 16 may include any integrated circuit components including a VLSIarray, processors, memory, photonic processing circuitry, etc.

A photonic waveguide layer 32 is integrated with the chip package byforming the photonic waveguide layer 32 on a backside of the IC chip 16to save real-estate for VLSI circuits on the chip 16. The photonicwaveguide layer 32 includes a core 26. Core 26 guides light therethroughand includes a high index of refraction relative to a cladding layer 28.The core 26 may include a polymer, SiN or other waveguide materials. Thecladding layer 28 may include any low index dielectric, SiO₂, polymer,porous materials, etc.

The photonic waveguide layer 32 is separated from the IC chip 16 by abarrier layer 20. The barrier layer 20 may include a thick layer of SiO₂(the thickness of the layer 18 should be greater than the lightwavelength (λ) to be transmitted by the core 26). Formation/depositionand patterning of the core 26 is performed on the barrier layer 20followed by cladding 28, which is deposited and encapsulates the core26. The barrier layer 20 isolates the core 26 from the VLSI circuits ofthe IC chip 16. The core refractive index needs to be higher than thematerial for the barrier layer 20, e.g., greater than 1.56 if SiO₂ isemployed as the barrier layer 20. Other materials may be employed forthe barrier layers 18 and 20.

Referring to FIG. 3, the package 30 is transferred to another mechanicalsubstrate 42 and flipped. The mechanical substrate 14 is removed toexpose the IC chip 16 to form a subassembly 60. The subassembly 60 ispositioned and bonded to a printed wiring board 46 or other platformusing solder balls 44 (C4) or other connections. The mechanicalsubstrate 42 may include Si, glass, sapphire, etc. and is bonded to thecladding 24 using an adhesive or the like. Instead of another mechanicalsubstrate, other substrates, layers or stacks of layers may be employed.

As shown for a subassembly 62, a mechanical substrate 14′ is reduced bypolishing or etching. A through via or vias 48 are formed therethrough.Another IC chip 50 with a substrate 52 may be bonded to the mechanicalsubstrate 14′ and be electrically connected to the IC chip 16 using vias48. The subassembly 62 is positioned and bonded to the printed wiringboard 46 or other platform using the solder balls 44 or otherconnections. It should be understood that photonics layers and IC layersmay be stacked in any combination for three dimensional (3D)integration.

The IC chips 16 include an open front-side available for C4 connections44, and can then be attached to the board 46 or Si carrier. The IC chips16 may have pads or connections 43 formed thereon to connect to solderballs 44 or other connection points.

It should be noted that any device may be connected to the through viaor vias 48. This may include a single component or an entire chip.

Referring to FIG. 4, another embodiment includes a stacked device 100with an IC chip 130 having III-V devices formed thereon or bondedthereto. The IC chip 130 may be formed on a SOI substrate or bulksubstrate. The IC chip 130 may include a light generating or emittingdevice 132 formed from the III-V material. The light emitting device 132may be part of another IC chip 116 or be a portion of a III-V substratebonded to the IC chip 130. The IC chip 130 extends across the device 100(or a portion thereof in this and other embodiments described herein)and has a barrier layer 120 formed on its back side. The barrier layer120 occupies thickness 106. The light emitting device 132 may include adiode or a laser, e.g., a vertical-cavity surface-emitting laser (VCSEL)or diode.

The IC chip 116 may be bonded to another IC chip 130 having transistors136 (FET) or other VLSI circuits formed thereon. The barrier layer 120is formed on the IC chip 130. The FET 136 of the IC chip 130 may beemployed to drive the light emitting device 132 on the IC chip 116.Metallizations 135 may be employed to make connections between the FET136 and the light emitting device 132. The barrier layer 120 may includeSiO₂, although other materials may be employed. The IC chip 116 mayinclude a dielectric material with a dielectric constant of between 2-4if SiO₂ is employed for the barrier layer 120 (SiO₂ has a dielectricconstant of about 3.9). A thickness 106 of the barrier layer is greaterthan the wavelength of light 108 emitted from the light emitting device132 and traveling in the core 126.

When joining the IC chips 116 and 130 with a photonics layer 123, thelight emitting device or devices 132 are aligned with the core 126 tocouple light 108 into the core 126. The core 126 includes a mirror 102.e.g., 45 degrees, to reflect light along a longitudinal direction in thecore 126. The vertical light emitting device 132 takes up less circuitarea real-estate than a planar device, but the mirror 102 is needed todirect light 108 from vertical to horizontal.

Cladding 128 includes a thickness 104 of greater than the wavelength oflight. A mechanical substrate 114 is employed to form the stack ofcomponents and to transfer the device 100 to another substrate orplatform. The IC chip 116 includes an open (unblocked) top surface 134for connecting to C4 connections.

Referring to FIG. 5, another embodiment includes a stacked device 110with an IC chip 130 having III-V devices formed thereon. The IC chip 130may be formed on a SOI substrate or bulk substrate. The IC chip 130 mayinclude a light generating or emitting device 132 formed from the III-Vmaterial. The light emitting device 132 may be part of another IC chip116 or be a portion of a III-V substrate bonded to the IC chip 130. Thelight emitting device 132 may include a photodiode or a laser. The ICchip 130 extends across the device 100 and has a barrier layer 118formed on its back side. The barrier layer 118 occupies thickness 107.

The IC chip 116 may be bonded to another IC chip 130 having transistors136 (FET) or other VLSI circuits formed thereon. The barrier layer 118is formed on the IC chip 130. The FET 136 of the IC chip 130 may beemployed to drive the light emitting device 132 on the IC chip 116. Thebarrier layer 118 may include SiO₂, although other materials may beemployed. The IC chip 116 may include a dielectric material with adielectric constant of between 2-4 if SiO₂ is employed for the barrierlayer 118 (SiO₂ has a dielectric constant of about 3.9). A thickness 107of the barrier layer is less than the wavelength of light 109 emittedfrom the light generating device 132 and traveling in a core 122.

When joining the IC chips 116 and 130 with a photonics layer 125, thelight emitting device or devices 132 are aligned with the core 122 tocouple light 109 into the core 122. The core 122 includes a transverseportion 121 and a mirror 102, e.g., 45 degrees, to couple and reflectlight along a longitudinal direction in the core 122. The vertical lightemitting device 132 takes up less circuit area real-estate than a planardevice, but the mirror 102 is needed to direct light 108 from verticalto horizontal.

Cladding 124 includes thicknesses 105 of greater than the wavelength oflight. The mechanical substrate 114 is employed to form the stack ofcomponents and to transfer the device to another substrate or platform.The IC chip 116 includes an open (unblocked) top surface 134 forconnecting to C4 connections.

Referring to FIG. 6, another embodiment includes a stacked device 200with an IC chip 230 having III-V devices formed thereon. The IC chip 230may be formed on a SOI substrate or bulk substrate. The IC chip 230extends across the device 200 and has a barrier layer 118 formed on itsback side. The IC chip 230 may include a light generating or emittingdevice 232 formed from the III-V material. The light emitting device 232may be part of another IC chip 216 or be a portion of a III-V substratebonded to the IC chip 230.

The light emitting device 232 may include a photodiode or a laser. TheIC chip 216 may be bonded to another IC chip 230 having transistors 236(FET) or other VLSI circuits formed thereon. The barrier layer 118 isformed on the IC chip 230. The FET 236 of the IC chip 230 may beemployed to drive the light generating device 232 on the IC chip 216.The barrier layer 118 may include SiO₂, although other materials may beemployed. The IC chip 216 may include a dielectric material with adielectric constant of between 2-4 if SiO₂ is employed for the barrierlayer 118 (SiO₂ has a dielectric constant of about 3.9). A thickness ofthe barrier layer is less than a wavelength of light 212 emitted fromthe light emitting device 232 and traveling in a core 222.

In this embodiment, the core 222 includes a portion 221 in contact withthe barrier layer 118 and close to the light emitting device 232 forevanescent light coupling. The light emitting device or devices 232 arealigned with a position of the core 222 to couple light 210 into thecore 222 through evanescent coupling. The core 222 includes an angledportion 221 to redirect light 212 along a longitudinal direction in thecore 222. The vertical light emitting device 232 takes up less circuitarea real-estate than a planar device, but the core 222 is shaped todirect light 210 to a horizontal direction.

Cladding 124 includes thicknesses 205 of greater than the wavelength oflight. The mechanical substrate 114 is employed to form the stack ofcomponents and to transfer the device to another substrate or platform.The IC chip 216 includes an open (unblocked) top surface 134 forconnecting to C4 connections of a carrier or board.

Referring to FIG. 7, another embodiment includes a stacked device 300with an IC chip 316. The IC chip 316 may be formed on a SOI substrate orbulk substrate. The IC chip 316 extends across the device 300. A barrierlayer 118 may be formed on a back surface of the IC chip 316. Thebarrier layer 118 occupies thickness 335.

A light generating or emitting device 332 may be formed from III-Vmaterial or other material and is bonded to the barrier layer 118. Thelight emitting device 332 may include a photodiode or a laser. The ICchip 316 may include transistors 336 (FETs) or other VLSI circuits andmetallizations 315 formed thereon.

The FET 336 of the IC chip 316 may be employed to drive the lightgenerating device 332. Metallizations 315 may pass through the barrierlayer 118 to make connections with the light generating device 332.After placing the light emitting device 332 on the barrier layer 118, afirst portion of the cladding layer 324 is formed followed by theformation of a core 322. The core 322 is aligned with the light outputof the light emitting device 332. Another portion of the cladding layer342′ is then formed over the core 322. The light emitting device ordevices 332 are aligned with the core 322 to couple light 310 into thecore 322. The core 322 may direct light off-chip or to other devices onthe device 300 (e.g., using transverse portions, not shown). The lightemitting device 332 takes up no real-estate on the IC 316.

Cladding 324, 324′ includes thicknesses 305 of greater than thewavelength of light employed. The mechanical substrate 114 is employedto form the stack of components and to transfer the device to anothersubstrate or platform. The IC chip 316 includes an open (unblocked) topsurface 134 for connecting to C4 connections.

The barrier layer 118 may include SiO₂, although other materials may beemployed. A thickness 335 of the barrier layer 118 may be greater than0.1 micron and is compatible with buried oxides in SOI devices (e.g.,approximately 0.15 microns in thickness).

Referring to FIG. 8, another embodiment includes a stacked device 400with an IC chip 416. The IC chip 416 may be formed on a SOI substrate orbulk substrate. A barrier layer 118 is formed on a back surface of theIC chip 416. The IC chip 416 extends across the device 400. The barrierlayer 118 occupies thickness 435.

A light generating or emitting device 432 may be formed from III-Vmaterial or other material and is bonded to the barrier layer 118. Thelight emitting device 432 may include a photodiode or a laser. The ICchip 416 may include transistors 436 (FETs) or other VLSI circuits andmetallizations 415 formed thereon.

The FET 436 of the IC chip 416 may be employed to drive the lightemitting device 432. Metallizations 415 may pass through the barrierlayer 118 to make connections with the light emitting device 432. Afterplacing the light emitting device 432 on the barrier layer 118, a firstportion of the cladding layer 424 is formed followed by the formation ofa core 422. The core 422 is formed on the light emitting device 432 tocouple evanescent light 412 into the core 422. Another portion of thecladding layer 442′ is then formed over the core 422. The light emittingdevice or devices 432 couple light 410 into the core 422. The core 422may direct light off-chip or to other devices on the device 400 (e.g.,using transverse portions, not shown). The light emitting device 432takes up no real-estate on the IC 416.

Cladding 424, 424′ includes thicknesses 405 of greater than thewavelength of light employed. The mechanical substrate 114 is employedto form the stack of components and to transfer the device to anothersubstrate or platform. The IC chip 416 includes an open (unblocked) topsurface 134 for connecting to C4 connections.

The barrier layer 118 may include SiO₂, although other materials may beemployed. A thickness 435 of the barrier layer 118 may be greater than0.1 micron and is compatible with buried oxides in SOI devices (e.g.,approximately 0.15 microns in thickness). The core 422 is close to thelight emitting device 432 for efficient evanescent coupling. Evanescentcoupling relaxes the alignment requirements between a planaroptoelectronics device (432) and core 422.

It should be understood that the embodiments described may include athin barrier layer or a thick barrier layer as needed. In addition, theICs may include planar FETs, finFETs or any other device type.

Referring to FIG. 9, a method for fabricating an optoelectronic deviceis shown in accordance with illustrative embodiments. In somealternative implementations, the functions noted in the blocks may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In block 502, a barrier layer is formed on a back side of asemiconductor substrate. A front side of the semiconductor substrateincludes an integrated circuit including electronic devices. Electronicdevice may include transistors (e.g., driving transistors, memorydevices, etc.), electromagnetic emission devices or any other componentsthat may be formed on an integrated circuit (metallizations, contacts,etc.). The barrier layer may include silicon oxide although othermaterial may be employed.

In block 504, a light emitting device (e.g., photodiode or laser) may bebonded to the barrier layer and formed within the cladding to couplelight into the core.

In block 506, a photonics layer is formed on the barrier layer. Thephotonics layer includes a core for transmission of light and a claddinglayer encapsulating the core. The cladding includes a different index ofrefraction than the core. The core is configured to couple lightgenerated from at least one component of the optoelectronic device,e.g., laser, photodiode, etc.

In one embodiment, the core may be formed directly on the barrier layerif the barrier layer includes a thickness greater than a wavelength ofthe light coupled in the core. In another embodiment, the cladding maybe formed directly on the barrier layer, and the core is offset from thebarrier layer within the cladding. The barrier layer in this instancemay include a thickness of less than a wavelength of the light coupledin the core.

The photonics layer may sandwiched between the integrated circuit and atleast one other electronic device. In block 508, connections may beformed through the barrier layer or through the photonics layer, e.g., athrough via or vias may be formed through the photonics layer, toconnect the integrated circuit to the at least one other electronicdevice (e.g., another IC, a light emitting device, a FET, etc.). Inblock 510, a light emitting device (e.g., photodiode or laser) may bebonded to the front side of the integrated circuit to couple lightthrough the barrier layer and into the core.

The optoelectronic device may be bonded to one or more other devicesusing a transfer process. In block 512, the optoelectronic device istransferred to a platform (e.g., a board, carrier, other chip, etc.).The front side of the integrated circuit is preferably free to connectto the board or carrier. The connections may include pads and solderballs (C4 connections). In useful embodiments, the integrated circuit isbonded to a first mechanical substrate. After forming the barrier layer,a photonics layer is formed. Then, the photonics layer is bonded to asecond mechanical substrate, and the first mechanical substrate isremoved (exposing a front side of the integrated circuit). The frontside of the integrated circuit is then connected to another device,board or carrier. The second mechanical substrate may remain or beremoved.

Having described preferred embodiments from integration of bondedoptoelectronics, photonics waveguide and VLSI SOI (which are intended tobe illustrative and not limiting), it is noted that modifications andvariations can be made by persons skilled in the art in light of theabove teachings. It is therefore to be understood that changes may bemade in the particular embodiments disclosed which are within the scopeof the invention as outlined by the appended claims. Having thusdescribed aspects of the invention, with the details and particularityrequired by the patent laws, what is claimed and desired protected byLetters Patent is set forth in the appended claims.

The invention claimed is:
 1. An optoelectronic device, comprising: anintegrated circuit including electronic devices and a semiconductorsubstrate, wherein the electronic devices are formed on a front side ofthe semiconductor substrate; a barrier layer formed on a back side ofthe semiconductor substrate, wherein the back side is opposite the frontside; and a photonics layer formed on the barrier layer such that thebarrier layer forms a barrier between the photonics layer and thesemiconductor substrate, the photonics layer including a core fortransmission of light and a cladding layer encapsulating the core andincluding a different index of refraction than the core, the coreconfigured to couple light generated from at least one component of theoptoelectronic device, wherein the cladding layer is formed on thebarrier layer and the core is offset from the barrier layer within thecladding layer and the barrier layer includes a thickness of less than awavelength of the light to be coupled in the core, wherein the light inthe core is coupled directly across the barrier layer from the at leastone component to the photonics layer.
 2. The device as recited in claim1, wherein the photonics layer is sandwiched between the integratedcircuit and at least one other electronic device and includes a throughvia to connect the integrated circuit to the at least one otherelectronic device.
 3. The device as recited in claim 1, wherein thefront side of the integrated circuit is free to enable connection to aboard or carrier.
 4. The device as recited in claim 1, wherein the atleast one electronic device includes a diode or laser bonded to thefront side of the integrated circuit to couple light through the barrierlayer and into the core.
 5. An optoelectronic device, comprising: anintegrated circuit including electronic devices and a semiconductorsubstrate, wherein the electronic devices are formed on a front side ofthe semiconductor substrate; a light emitting device connected to atleast one of the electronic devices; a barrier layer formed on a backside of the semiconductor substrate, wherein the back side is oppositethe front side; and a photonics layer formed on the barrier layer suchthat the barrier layer forms a barrier between the photonics layer andthe semiconductor substrate, the photonics layer including a core fortransmission of light and a cladding layer encapsulating the core andincluding a different index of refraction than the core, the coreconfigured to couple light generated by the light emitting device,wherein the cladding layer is formed on the barrier layer and the coreis offset from the barrier layer within the cladding layer and thebarrier layer includes a thickness of less than a wavelength of thelight to be coupled in the core, wherein the light in the core iscoupled directly across the barrier layer from the light emitting deviceto the photonics layer.
 6. The device as recited in claim 5, wherein thelight emitting device includes a III-V substrate bonded to one of thefront side of the integrated circuit or the barrier layer.
 7. The deviceas recited in claim 5, wherein the photonics layer is connected to theintegrated circuit through the barrier layer.
 8. The device as recitedin claim 5, wherein the front side of the integrated circuit is free toenable connection to a board or carrier.
 9. The device as recited inclaim 5, wherein the light emitting device includes a diode or laserthat couples light through the barrier layer and into the core using oneof a mirror or transverse portion.
 10. The device as recited in claim 5,wherein the light emitting device includes a diode or laser that isformed on the barrier layer and couples light into the core.
 11. Amethod for fabricating an optoelectronic device, comprising: forming abarrier layer on a back side of a semiconductor substrate of anintegrated circuit, a front side of the semiconductor substrateincluding electronic devices, wherein the back side is opposite thefront side; and forming a photonics layer on the barrier layer such thatthe barrier layer forms a barrier between the photonics layer and thesemiconductor substrate, the photonics layer including a core fortransmission of light and a cladding layer encapsulating the core andincluding a different index of refraction than the core, the coreconfigured to couple light generated from at least one component of theoptoelectronic device, wherein the cladding layer is formed on thebarrier layer and the core is offset from the barrier layer within thecladding layer and the barrier layer includes a thickness of less than awavelength of the light to be coupled in the core, wherein the light inthe core is coupled directly across the barrier layer from the at leastone component to the photonics layer.
 12. The method as recited in claim11, wherein the photonics layer is sandwiched between the integratedcircuit and at least one other electronic device and the method furthercomprises forming a through via to connect the integrated circuit to theat least one other electronic device.
 13. The method as recited in claim11, further comprising transferring the optoelectronic device to a boardor carrier front side and connecting the front side of the integratedcircuit to the board or carrier.